A NUMERICAL GLOBAL METEOROLOGICAL SULFUR TRANSPORT MODEL AND ITS APPLICATION TO ARCTIC AIR-POLLUTION

The paper describes the construction of a dynamic atmospheric sulfur t ransport model and addresses the issue of long-range atmospheric sulfu r transport to the Arctic as an application of the model. The global m odel includes the dynamics of meteorologial and tracer fields, thermod ynamics, cloud processes, turbulent boundary layer mixing, multiple th ree-dimensional anthropogenic sulfur emission sources, dry and aqueous -phase chemical processes for sulfur, dry deposition and the precipita tion scavenging of sulfur. So Far, the incomplete description of cloud s and precipitation has been a major limitation to the modeling of wet chemical processes on the global scale. One of the main features of o ur study is an attempt to a realistic representation of the interactio n between clouds and chemical reactions. The model includes a derailed sub-grid scale convective and stratiform condensation scheme which in cludes cloud liquid water content as a predictive variable. It is show n that the model is able to reproduce important dynamic and physical s tructures in the atmospheric circulation leading to a realistic simula tion of the important aspects of the long-range transport of sulfur to the Arctic. Realistic simulation of seasonal variations in atmospheri c Bow and cloud related processes provides reliable estimates of the s ulfur deposition fluxes and reproduces the characteristic annual cycle of sulfur concentrations over the Arctic. Zonally averaged fields for the source and Arctic regions reveal important differences in the lon g-range transport mechanisms in different seasons. The model represent s a powerful tool for further examining the mechanisms of sulfur trans port and its impact on the atmosphere.